Data logger and Sensors for Agriculture

 There are vast number of companies producing data-loggers for agriculture. The top most provider is campbell scientific the loggers are the best in performance supports all types of sensors but they are very costly and operation is not user friendly.

Sensors come in different electrical designs, for example Supply Voltage / excitation voltage: some of the sensors work on 3 volt supply some others on 5 or 12v some sensors support 5 to 12v . Loggers are installed in remote fields and expected to work unattended for one or two years. So the power consumption is important which is affected by Current Consumption of the sensors. Normally moisture sensors use 10-16mA. So the sensors are switched off by the logger program i.e. called Power Cycling. Some users unaware about this facility in loggers the connect the supply lines together which means all sensors powered up at a time consuming more power.we are not reading all sensors at a time, its one by one so power should be so. Some digital sensors Hibernate(sleep mode) themselves when there is no read signal. These type of digital sensors specify two different power consumption in spec sheet 1.Read time Current, 2.Sleep/Standby Current. Sensor Ouput Voltage  Range of analog sensors vary from 0-1v 0-2.5v 0-3v 0-5v. The data logger should support all these, if the logger has no option for small voltage ranges then the logger readings may achieve less accuracy. Sensor Output Proportionality also different for analog sensors some sensors come with internal voltage reference so the output is independent of Supply voltage and in some cases its proportional to input Supply Voltage. In digital sensors the voltage level is always in TTL level so these factors does not affect.